1. Field of Invention
This invention relates to airgun methods and apparatuses, the type of which are used for projectile propulsion, and specifically to those airguns having means to launch successive projectiles without reloading and/or re-cocking the device, principally via a single continuous trigger activation (fully-automatic) and repetitive trigger activation per projectile launch (semi-automatic).
The ability of both semi and fully-automatic modes in the same device is commonly known as “selective-fire,” which is a term most commonly used for firearms but is sometimes applied to other projectile propulsion devices (such as airguns), and is used herein for that purpose.
The term “airgun” is commonly used (and is used herein) to describe all projectile launching devices using any fluid and/or any variety or combination(s) of fluids for propellant (such as nitrogen, helium, CO2, etc.) and is not exclusive to devices powered specifically by “air;” it represents a convenient and popular term used to classify all such fluid powered devices.
The term “BB” is commonly used (and is generally used herein unless otherwise specified) to describe metallic round shot of various calibers, unless such is otherwise specified as plastic or another material (this is a more general definition than the formal term “BB” which can more specifically indicate approximately 0.177 caliber round shot). The term “pellet” is commonly used (and is generally used herein unless otherwise specified) to describe any other type of shot, as for instance cylindrical and/or “bullet shaped” steel, lead, plastic, and/or any other type of shot.
2. Prior Art
Projectile propulsion methods using fluid propellants either pre-stored or otherwise initiated to become above-ambient pressure (such as air, nitrogen, helium, CO2, refrigerant vapors, steam, flash/catalyst heated fluids, compression heating, and so forth) have a long history. In general, these use a predetermined means to direct an above ambient pressure propellant into a breech in order to propel a projectile placed into the breech through a barrel, thereby causing it to travel at a some velocity. All such devices (including the present invention described herein) are now referred to and classified as “traditional airguns.”
The foundational physical principles of airguns may be similar across devices, but the methods of their implementation and application can vary significantly. Airgun methods which launch projectiles successively via cycling the action automatically when given a single continuous trigger activation (fully-automatic operation) are rare in the prior art when compared to single-shot and/or semi-automatic units, and selective-fire versions (those having both semi and fully-automatic modes) are even more rare. Moreover, all known automatic airgun methods suffer from significant drawbacks.
Due to inefficiencies and complexities of all-mechanical propellant-driven automatic airguns, improved methods were developed which incorporated electrical means for controlling the propellant flow within such devices; examples begin circa 1937 with the MacGlashan BB Gun, and continue through today, yielding two popular classes of such electro-mechanical automatic airgun methods—motorized spring-air automatic airguns and “pre-charged” automatic airguns using electro-mechanical actuators (the latter being similar to the MacGlashan BB Gun).
Motorized Spring-Air Automatic Airguns
Motorized spring-air guns use an electric motor driven spring-piston type system to rapidly compress and thus heat air which generates the necessary above ambient pressure propellant. Current devices utilizing such methods are complex, inefficient, and relatively heavy. They require motors, pistons, gears, and sliding seals involving precision machining of mechanical components which wear and are difficult to manufacture; they generate their muzzle energy from a conversion of electrical-to-mechanical energy, the power sources of which typically have relatively low power density (usually common batteries).
Although I have developed several improvements within this class that show promise for achieving higher power and better efficiencies, when using the known techniques and existing common power sources, resulting devices are generally confined to the relatively low-power domain, and remain more complex, difficult to manufacture, and more expensive than other possible implementations—namely pre-charged systems.
Pre-Charged Automatic Airguns Using Electro-Mechanical Actuators
Pre-charged automatic airguns using electro-mechanical actuators (such as solenoids) use such electro-mechanical actuators to control a valve system which subsequently controls the flow of propellant for creating the projectile motive force; the system is controlled electronically to allow repeat cycling of the action. The numerous and particular arrangements, types, combinations and improvements of valve means, actuator means, and control means (with examples starting from circa 1937 with the MacGlashan BB Gun) are what separates these methods in the prior art.
Common Modern Valve Classes for Electro-Mechanical Automatic Airguns
In electro-mechanical automatic airguns today, there are two major valve-type subclasses: poppet-valves and spool-valves (both commonly encountered in paintball gun applications). However, all prior art automatic airgun methods using these valving types (and all other valving types) have major shortcomings and drawbacks.
In the case of poppet-valve electro-mechanical automatic airguns, a hammer, which is either driven mechanically and/or activated electrically, or directly driven by an electro-mechanical actuator (typically a solenoid) or otherwise driven via an arrangement of other electro-mechanically actuated valves and/or connected to a fluid-driven ram, is used to strike open a poppet valve to allow flow of propellant for providing motive force. This system has several drawbacks. First, it generally requires (at minimum) a sliding seal and/or elastomer valve seal for the poppet-valve control pin (and/or actuator ram) and an impact surface for the hammer, adding critical manufacturing and wear points. Next, the poppet valve response is a function of the impact force, mechanical return spring force, frictional forces, and propellant reservoir pressure—thus, precise control can become relatively difficult in the basic implementations and additional mechanisms are often required to insure shot consistency; this can become more pronounced with high firing rates. In existing embodiments, such poppet valve methods as used on automatic airguns require higher operating pressures (and are more noisy) than compared to other methods; they can additionally exhibit high vibration depending on the implementation.
In the case of spool-valve electro-mechanical automatic airguns, a tubular sliding valve (the spool-valve) is controlled by an electrical actuator (typically a solenoid), and/or a complex arrangement of electro-mechanically and/or fluid actuated valves, to route the propellant via a relatively intricate series of porting and/or venting through the valve (and often associated sub-reservoirs) with the valve also typically acting as a bolt (to control the loading of projectiles) and serving as a valve outlet port. Spool-valve designs generally require multiple sealing surfaces, intricate sliding seals, precision porting, and the resulting increased cost and complexity in manufacturing; they tend to be less reliable, more complex, less efficient, higher maintenance, and subject to faster wear then their poppet-valve counterparts. All currently known designs using spool-valve/bolt loaded projectiles require further throw than typical with a solenoid and thus must control the bolt's movement via fluid porting, thus creating significant complexity. But, such spool-valves also typically provide less vibration, quieter operation, and allow significantly lower operating pressure requirements than poppet-valves.
General Background on Pre-Charged Electro-Mechanical Automatic Airgun Methods
Electro-mechanical techniques (and electric valve actuation) have a long history in a variety of airgun applications. As such, there are several related electro-mechanical automatic airgun methods known in the art, but all have significant drawbacks and shortcomings.
The earliest of these is the MacGlashan BB Gun circa 1937 which utilized an electro-mechanical plus pneumatic piston arrangement and solenoid actuator to route propellant to the breech; it is in many ways similar in operation to the aforementioned spool-valve systems with a somewhat different valve arrangement and generally more complex mechanical operation. This airgun used an involved arrangement of levers, pistons, ports, sliding seals, position sensors and feed systems to realize the method; it was very intricate, generally inelegant, and did not have any provisions for selective-fire.
U.S. Pat. No. 3,695,246 (1971) describes a relatively complex automatic “pellet” gun (but apparently functional only with round shot BBs or paintballs) which also uses electro-mechanically operated valves for propellant channeling. The control system is largely inelegant and comprises components using complex electro-mechanical arrangements. The automatic cycling method and feed system is significantly more complex than in other methods; it necessitates optoelectronic sensing, alternating drive current, and precision machining. The device is full of linkages, chains, clutches, and other mechanisms and does not lend itself to portability or selective-fire operation.
U.S. Pat. No. 5,727,538 (1996) also describes an automatic airgun using electronic valve actuation, and is similar to the MacGlashan design in this regard and several other respects. For instance, both devices incorporate mechanical position sensing in reciprocating components which couple to the firing cycle. Further, U.S. Pat. No. 5,727,538 not only relies on the requirement of a reciprocating bolt for its automatic operational method, but also that the bolt must have a “through aperture to allow passage of compressed gas” for operation. This requirement limits the effective valve orifice size, increases propellant flow losses, and increases dead-space; the patent also notes the requirement of electronic detection of both the bolt and projectile positions, adding additional complexity to the device (and thus coupling the mechanical action to the firing sequence).
A selective-fire, burst-mode electro-mechanical automatic BB gun made by Baikal called the “Drozd” uses an electrically powered solenoid-driven hammer-based poppet valve—and, it possesses several of the corresponding limitations as noted earlier (including sliding seals and impact surfaces). It employs part of the valve as a projectile feeder pin (similar in this regard to U.S. Pat. No. 5,727,538) and inverts the poppet; this serves to help the projectile feed mechanism but creates a flow restriction which reduces the effective valve orifice size and can lower performance. Further, the valve activation and dwell times are coupled and generally controlled by the hammer impact and the mechanical response time of the valve return spring and internal pressure, resulting in a relatively limited adjustment range without resorting to mechanical means or more complex control circuitry. Moreover, there is no straightforward provision or alternative mode for preventing propellant from entering the projectile magazine given its method.
The above generally represent the simplest and most comprehensive examples of methods for electro-mechanical automatic airguns found in the prior art—and clearly, none are very simple. It has so far proved impossible (since at least circa 1937 and until this present invention) for anyone to create an electro-mechanical automatic airgun less complex than those described, let alone one which addresses the typical shortcomings and drawbacks inherent to each method.
In addition to their respective shortcomings, drawbacks, and complexities, none of the known prior art methods incorporate all the elements and advantages of pre-charged fluids, non-impact valve actuation, unobstructed breech porting, and valve control means with selective-fire operation—even irrespective of their typically high complexities. All examples of prior art contain certain elements which preclude straightforward integration of these advantageous aspects.
None of the above electro-mechanical automatic airgun methods suggest provisions for launching pellets (as defined herein) or otherwise non-round projectiles in a fully-automatic fashion.
Therefore, regardless of the approaches, all of the prior methods have significant shortcomings, drawbacks, and limitations. It must be additionally noted that most implementations are more complex and intricate than the basic methods recounted, which indicates additional inelegance and shortcomings of the prior art.
In specific application domains, the extremely limited examples of action-cycling pre-charged fully-automatic BB/pellet airguns is a testament to the difficulty in cost-effectively creating such devices and is largely due to the inherent complexities when compared to their single-shot and semi-automatic counterparts.
As noted, prior art embodiments of particular individual classes of airguns as described above are typically generally similar to each other within each class, but are further modified in each individual embodiment to improve performance, simplify construction, lower cost, and/or to achieve other purposes; all known prior art has not been entirely satisfactory in some aspects. As such, the overall automatic airgun domain is largely confined to complex, intricate, and expensive paintball guns or low-powered, electro-mechanical airsoft guns with few exceptions. Accordingly, a need exists for automatic airgun methods and apparatuses which deliver improved performance, reduced complexity, simplified construction, less expensive manufacture, more flexibility, wider applicability, and greater reliability.
Therefore, while preexisting airgun methods may be suitable for the purposes for which they where designed, they would not be as suitable for the purposes of the present invention as heretofore described. In conjunction with and in addition to the drawbacks already noted, the prior art fails to satisfy all the needs in the art and is not suitable for the purposes of the present invention; as such, improved methods and mechanisms are required to alleviate continuing deficiencies.